From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B91D664DC; Fri, 9 Feb 2024 09:12:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707469925; cv=none; b=SLGLm3q6e4iQshz9oP774zqQ1kU53B9YWvTR4tiCKs1OraQS70xqW4tM6rQ+SyXMRuWKQC7mnnL/8Hk2ubgHFDmWc7AFrDNYoNJVCSlIHwzESyqCumHLmj9C0HUAZwo3VzhpqxinjyGRCzcVGHoQbvQ2NlVjn9wZCIdP+LUy/7E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707469925; c=relaxed/simple; bh=theZ6OspXm/0i2No8y+xI4YUDPJBFyxgE/uTf9ebaKo=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=fcaFsXpl3w4VF54aJBfzW+XPFMwSI1Jtf8jomPpD2kG+/uPIhuVRsERVJD9D1Yns2PXkbByKOzBLhTVQHBkf/vv6by9EXef6h23RuRGfQmdNee8TAPmA4h5T7VVjNJR0Hle7xxg1dFTS8a+Q3gQmw3qAyyfMGjDGVxro1mmdgnE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=U2LuSMWC; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=eo7fJWGN; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="U2LuSMWC"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="eo7fJWGN" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1707469920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Zsx4SlJA6ViAZgBmFf5oMXtVVZcOurzD7dailCPOcmg=; b=U2LuSMWCG4aTaxIS9EQYvjlfYf14ZGG3yAMpC/LSEdZPbr8hVLGYAilg8kGMb8WRZDgZLW xWQD7ZScqQqJwX18sMtobZaOz9e31KI74X01msggG0VaoAGIaUp89kQe7DaHW2vaGG9pqJ TtRJ7nKl5HeqT4pbOdw52NulBGFw/SFDFBU5qxb5JUy6To4FdrWYuX/Vz93fwuGnMU/Bsj 5llch7OaHv9c/+w6xkhe3Kh5lgfQazBJoG1ywmBPy9+TZ6iT2t3yHxJpmFe4txXIn/S39E 8XBhoEz1clbH75ZHF7NFLejLK/Hb8qDIORb3ff2k/8QfA4ZDeBaMvctc4uRffA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1707469920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Zsx4SlJA6ViAZgBmFf5oMXtVVZcOurzD7dailCPOcmg=; b=eo7fJWGNe451HcaD4JeMH+h14mreK0oBdwPxhWnIFTUYXZaC7WARkMC9JqNm7FBaok4/1c OOolCXi6PyPZsqDQ== To: "John B. Wyatt IV" Cc: Petr Mladek , Clark Williams , jlelli@redhat.com, Derek Barbosa , "John B. Wyatt IV" , LKML , linux-rt-users Subject: Re: NMI Reported with console_blast.sh In-Reply-To: References: Date: Fri, 09 Feb 2024 10:17:48 +0106 Message-ID: <87v86yc88b.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Hi John, On 2024-02-07, "John B. Wyatt IV" wrote: > You asked me to test the upstream kernel with a printk torture > (console_blash.sh) with the different scheduler settings on a very > large core system. Wanted to post to the mailing list to show what I > tested with. Thanks for your efforts here! > As far as I can tell; all the scheduler settings correctly get to and > trip the sysrq trigger to make it crash at the end of the script. > > But, with every state, except for fully pre-emeptive, I got an NMI > call trace before the sysrq trigger that expectedly crashes the > system. > > This is on a Fedora 39 Server installed on a 2x56 core, 224 thread > machine in Red Hat's lab with the lscpu below with 6.7.0-rt6. I have > only decoded and attached NoForcedPreemption below. Please ask if you > want additional ones but they all look similar when I checked. > > NMI Call Trace for NoForcedPreemption > --- > task:cpuhp/222 state:S stack:0 pid:1349 tgid:1349 ppid:2 flags:0x00004000 > Call Trace: > > __schedule (kernel/sched/core.c:5396 kernel/sched/core.c:6708) > ? try_to_wake_up (./arch/x86/include/asm/preempt.h:104 ./include/linux/preempt.h:484 ./include/linux/preempt.h:484 kernel/sched/core.c:4217) > ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) > schedule (kernel/sched/core.c:6784 kernel/sched/core.c:6798) > smpboot_thread_fn (kernel/smpboot.c:160) > kthread (kernel/kthread.c:388) > ? __pfx_kthread (kernel/kthread.c:341) > ret_from_fork (arch/x86/kernel/process.c:147) > ? __pfx_kthread (kernel/kthread.c:341) > ret_from_fork_asm (arch/x86/entry/entry_64.S:250) > > sysrq: Trigger a crash > Kernel panic - not syncing: sysrq triggered crash > NMI backtrace for cpu 56 > Hardware name: Intel Corporation D50DNP1SBB/D50DNP1SBB, BIOS SE5C7411.86B.9409.D04.2212261349 12/26/2022 > RIP: 0010:io_serial_in (arch/x86/kernel/early_printk.c:100) I am curious why early_printk is here. Are you using KDB or KGDB? Could you provide me your kernel config and boot args? On a side note, it is helpful to use a kernel that prints timing and caller information: CONFIG_PRINTK_TIME=y CONFIG_PRINTK_CALLER=y Timing information can also be turned on dynamically with the boot arg "printk.time=1" but the caller information (which is more interesting) can only be enabled in the kernel build. John Ogness